1. Technical Field
The present invention relates to a technique for detecting a foreign matter present on a medium in a liquid discharge apparatus for discharging a liquid from a head onto a medium supported by a support member.
2. Related Art
There is a known printing apparatus provided with a support member for supporting a medium and a head that faces the support member, printing being performed onto the medium by the discharging of ink from the head onto the medium supported on the support member. Such a printing apparatus executes printing onto the medium while also conveying the medium between the support member and the head. At this time, if a foreign matter is present on the medium, the foreign matter may end up coming into contact with the head and damaging the head. In light of such circumstances, techniques for detecting a foreign matter present on a medium have long been proposed.
For example, a foreign matter detection apparatus of Japanese laid-open patent publication No. 2012-71962 is provided with a conveyance roller for conveying a continuous document, and a movable roller that faces the conveyance roller, the continuous document being nipped between the movable roller and the conveyance roller. The movable roller can be displaced in a direction of approach towards or withdrawal from the conveyance roller; if a foreign matter present on the continuous document passes between the movable roller and the conveyance roller, the movable roller is pressed and displaced by the foreign matter. As such, the foreign matter can be detected on the basis of the displacement of the movable roller.
In a configuration for thus detecting a foreign matter on a medium on the basis of displacement of a movable roller nipping the medium with a support member on the other side, it becomes more difficult to detect the foreign matter on the medium if there is a vacant clearance between the medium and the movable roller. However, there are instances where, for example, the surface of the support member ends up being inclined due to causes such as thermal deformation, creating a vacant clearance between the movable roller and the medium supported by the support member, and lowering the accuracy of detection of a foreign matter present on the medium.